Later in his career, Relph worked as a producer. He served as associate producer on the Ealing comedy Kind Hearts and Coronets (1949) ; and had a significant 20-year partnership with Basil Dearden beginning in 1949 and ending with Dearden's death in 1971.[7] From 1972 to 1979, he was chairman of the British Film Institute's Production Board.[8]

His son, Simon Relph, is also a film producer and former chairman of BAFTA.[4] His daughter, Emma Relph, had several parts on television and in the films as an actress during the 1980s.[9]